The M.A.S. Newsletter

Journal of the Mauritius Astronomical Society


November 98

The Leonid Meteor Shower and Comet 55P/Tempel-Tuttle:

There is NO meeting, scheduled for the Leonid meteor storm on Tuesday 17th of November. Members are advised to organize their own observations from a dark location, where there is a clear view to the north east. According to calculations, the peak activity will occur on the 17th at 7hr21 pm GMT. The predicted visible rate is at a limiting magnitude of 6.5 for a local time of 3hr30 am for the night November 17 - 18. This prediction should not be relied upon, and we should be prepared for the full range of activity from any location. We therefore advise members to start their observations at 11hr00 pm and continue, if possible, ...till dawn.

The interest of serious observers in meteor showers intensified in 1833 with the Leonid meteor storm. The moderately active Leonid meteor shower has a normal maximum of 15 per hour. But every thirty three years, when the interior of the solar system is revisited by the parent comet 55P/Tempel-Tuttle, the Earth crosses the densest concentration of meteors and a storm often results. At 71 kms-1, these are the fastest major shower meteors. They also offer the consistently brightest meteors of any annual shower, which frequently leave persistent trails.

Scientific Contributions:

This meteor storm may be the ideal opportunity to start astronomical photography. Photographs do not only look nice, but also contain valuable information about the position of meteors. For meteor photography, all you need is a camera with time exposure capability, fitted with a 50mm ordinary lens and its tripod. The film should be of very high sensivity (high ISO number i.e. 800, 1600 or higher), and the time exposure will be of 10 to 15 minutes from a dark place. The camera should be pointed 45-60 degrees from the radiant (here the radiant is the neck of the Lion). Note the time of start and end of each exposure, and if you are lucky to catch a fireball, it is advisable to finish the exposure immediately (noting the time) in order to avoid later disturbances. For contributing to the photographic database you can contact via E-mail:

Jürgen Rendtel

You can have also access to this highly comprenhensive site devoted to meteor shower observations:

http://www.imo.net

It is the home page of the International Meteor Organization (IMO).

Software to check your capabilities of monitoring meteors at storm level can also be found at:

ftp://www.imo.net/pub/software/metsim

Video Observation of Meteors:

Video observation is one of the most advanced techniques in meteor observation. What you need is a fast lens, a powerful image intensifier and a video camera. Those of you who possess the above equipment are invited to visit the IMO site mentioned earlier.

Yet Another Meteor Shower:

Alpha Monocerotides is the name, 22-23 November is the date. This shower, which is usually insignificant, was observed in 1995 to have a brief but remarkable maximum of some 400 shooting stars in 5 minutes! The outburst of activity is suspected to have a periodicity of 10 years. The radiant, which is high enough at 11hr00 pm, is found some 15º north east of the star Sirius.

The sky this month:

On the 27th of November at 6hr30 pm, the planets Mercury (2.7mag, 7% illuminated) and Venus (-3.9mag, 99% illuminated) are at 7º and 6º respectively above western horizon. They are in conjunction on the following evening at sunset. The asteroid Ceres at 7.0mag (visible through binoculars and small telescopes) visits the Hyades in the early December. Its motion through the Hyades can be followed during the days preceeding and following the 1st of December, when it is at its closest approach.

Serge Florens, Secretary

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